o2 sensors

Z71Silverado · February 5, 2012

About a year ago. I went from getting 15-16 miles a gallon to 12. I put in new knock sensors after my engine light kept coming on but it didn't fix the gas problem. I want to put in new o2 sensors and see if that's the problem. Is there an o2 sensor on each pipe coming off the engine?

Morgan1986 · February 5, 2012

nice looking truck .

Carder09 · February 5, 2012

I believe there is four, two before each cat and two after, being two per side. Though I can't remember if the front ones are more important that the back ones

zedbear · February 5, 2012

The front ones are the ones you want in this case. Rear ones just monitor catalyst efficency.

Babyhauler · February 6, 2012

Just replaced my front ones. I posted pics to get info based on how they looked. I guess you can't tell and read them like a spark plug. I had replaced knock sensors a few weeks ago also. Only a 1/4 tank used with the new O2's, but it does seem to run a little smoother. I keep accurate mileage records & will soon know a difference.

Babyhauler

Z71Silverado · February 6, 2012

Just replaced my front ones. I posted pics to get info based on how they looked. I guess you can't tell and read them like a spark plug. I had replaced knock sensors a few weeks ago also. Only a 1/4 tank used with the new O2's, but it does seem to run a little smoother. I keep accurate mileage records & will soon know a difference.

Babyhauler

How many miles were on your truck when you replaced? I had 75,000 when I needed new knock sensor. The back one was really rusty and the front one was fine. I put new ones in both and sealed them up with high temp silicone. The truck now has 86,000 miles and it runs alright but when at idle, rpms dip up and down very slightly. I was thinking it's the o2 sensor or it may need a tune up. The truck is a 2004.

AirForceAngler · February 6, 2012

About a year ago. I went from getting 15-16 miles a gallon to 12. I put in new knock sensors after my engine light kept coming on but it didn't fix the gas problem. I want to put in new o2 sensors and see if that's the problem. Is there an o2 sensor on each pipe coming off the engine?

Did you find out why your check light was coming on in the first place? This would be a good first step instead of just replacing parts.

Z71Silverado · February 6, 2012

About a year ago. I went from getting 15-16 miles a gallon to 12. I put in new knock sensors after my engine light kept coming on but it didn't fix the gas problem. I want to put in new o2 sensors and see if that's the problem. Is there an o2 sensor on each pipe coming off the engine?

Did you find out why your check light was coming on in the first place? This would be a good first step instead of just replacing parts.

It was coming on because of the knock sensors.

Babyhauler · February 8, 2012

Knock sensors were replaced last month at about 190,000 miles. Code was coming on & rough idle. My GM tech says O2 service life is about 100,000 miles. Your probably getting about time for plugs and wires as just normal maintenance. Change the O2's first, then see how it runs for a few weeks. The MAF and throttle body need to be cleaned regularly and correctly. I run Chevron fuel 99% of the time to get better mileage and keep problems away. A lot of folks here run extra cleaners in their fuel also. Your driving style and conditions can cause some of these items to come due early or later. Maintenance is cheaper than a new payment.

Good luck

Babyhauler